Apparatus for mounting an object to a structure in a vibration-free manner

ABSTRACT

The invention relates to a device for mounting an object to a structure in a vibration-free manner. The device has an elastic arrangement that supports the object at the structure in a stiff manner in the directions of at least two of the total of six translational and rotational degrees of freedom and in a soft manner in the directions of at least one of the total of six translational and rotational degrees of freedom. Main modes of motion of the object in the directions of the rigid support have natural frequencies that are higher than any main mode of motion of the object in any direction of the soft support at least by a factor of ten. The soft support is undamped, and a damping device is provided for any main mode of motion of the object in any direction of the soft support.

CROSS REFERENCE

This present invention is a continuation-in-part (CIP) of InternationalPatent Application PCT/EP2012/052283 entitled “Mounting an Object on aStructure in a Vibration-Free Manner” with an International Filing Dateof Feb. 10, 2012 and claiming priority to German Patent Applications DE10 2011 000 656.7, filed on Feb. 11, 2011, and German Utility ModelApplication DE 20 2011 000 635.2, filed on Mar. 21, 2011, both entitled“Schwingungsfreie Lagerung eines Objekts an einer Struktur”.

FIELD OF THE INVENTION

The present invention relates to an apparatus for mounting an object toa structure in a vibration-free manner, the apparatus comprising anelastic arrangement supporting the object at the structure.

The present invention particularly relates to an apparatus for mountingan object to a structure in such a way that the object—despite beingmounted in a vibration-free manner in one or more directions—followsmovements of the structure in other directions. This means that theobject is rigidly guided by the structure in these other directions.Typically, no vibrations occur in these other directions so that thereis no need of avoiding a transfer of these vibrations between the objectand the structure in these other directions.

BACKGROUND ART

It is known for various currently produced motor vehicles, particularlyminibuses and trucks, that vibrations of the mirror glass of an exteriorrear view mirror of these motor vehicles may occur in a frequency rangeof 10 to 80 Hz and at a considerable amplitude which has to beconsidered as being critical.

It is further known that mirror glasses of exterior rear view mirrors ofmotorbikes intensively vibrate in specific motor rotation speed rangesto such an extent that the exterior rear view mirrors lose theirfunction and the driver of the motorbike has to turn around for viewingbackwards.

Besides approaches to stiffen the support of the mirror glass of therespective exterior rear view mirror at the body of the motor vehiclesuch that relative vibrations of the mirror glass with regard to thebody do no longer occur, it is also known to attenuate occurringvibrations of the mirror glass of the exterior rear view mirror by meansof a friction damper (see for example DE 101 43 976 B4 or DE 198 03 459A1) or by means of a vibration absorber (see for example DE 42 00 744C2). Whereas the efficiency of friction dampers strongly depends on theweather, particularly on atmospheric moisture and temperature, frictiondampers often do not achieve a sufficient lifetime, and friction dampersalso transfer disturbing forces from the body onto the mirror glass ofthe exterior rear view mirror, vibration absorbers are only effective ina small range of frequencies around their absorber eigenfrequency.

Active measures for suppressing vibrations are also known. They useactivatable functional materials to apply forces to a mounted object tokeep the object at rest by means of adjusting a sum total of the forcesacting on the object to zero. Such an active vibration suppression doesalso not have a very large range of efficiency. Here, however, rather alimitation with regard to the coverable amplitudes is given than withregard to the coverable frequencies. This particularly applies, if, dueto interposed adjusting and retracting mechanism for example, a mirrorglass of an exterior rear view mirror can not be essentially rigidlymounted to the body of a motor vehicle.

U.S. Pat. No. 5,492,313 discloses flexure bearings for reciprocatingcomponents of cryo coolers. These bearings were first applied withspiral-cut diaphragms. According to U.S. Pat. No. 5,492,313 A, suchflexure bearings for reciprocating machines comprising a translating cutdiaphragm with circumferential tangent cantilever flexure blades securedbetween rim and hub spaces are improved by symmetrical opposing endangles and ends equally displaced from radial lines extending from thecenter of the diaphragm.

DE 197 23 515 A1 comprises an elastic element with leaf springs for aconnection of two parts which is elastic in one direction of motion. Aplurality of such elastic elements which are arranged at a distance inthis direction of motion can be used for mounting an object to astructure such that the object is softly supported at the structure inthis direction of motion whereas it is rigidly guided by the structurein all other directions.

There still is a need of an apparatus for mounting an object to astructure in a vibration-free manner, which has general advantages, likefor example in mounting an object subjected to aerodynamic loads to thebody of a motor vehicle.

SUMMARY OF THE INVENTION

The present invention relates to an apparatus for mounting an object toa structure in a vibration-free manner. The apparatus comprises anelastic arrangement configured to provide a stiff support for the objectat the structure in the directions of at least two of a total of sixtranslational and rotational degrees of freedom, and a soft support forthe object at the structure at least in the directions of onetranslational degree of freedom. Each main mode of motion of the objectin any direction of the stiff support comprises an eigenfrequency whichis by a factor of at least ten higher than any eigenfrequency of anymain mode of motion of the object in any direction of the soft support;and the elastic arrangement is undamped in each direction of the softsupport. The apparatus further comprises an attenuation device for anymain mode of motion of the object in any direction of the soft support.

The present invention further relates to an apparatus for mounting anobject to a structure, the apparatus comprising an elastic arrangementincluding at least two elastic partial arrangements arranged at adistance in the direction of a main axis. The elastic partialarrangements are soft in the direction of the main axis and stiff in alldirections orthogonal to the main axis. Each elastic partial arrangementcomprises an inner connection area close to the main axis and an outerconnection area farther away from the axis; and each elastic partialarrangement comprises at least two leaf springs which extend between theinner connection area and the outer connection area and which arespirally wound into each other within a common leaf plane.

Other features and advantages of the present invention will becomeapparent to one with skill in the art upon examination of the followingdrawings and the detailed description. It is intended that all suchadditional features and advantages be included herein within the scopeof the present invention, as defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood with reference to the followingdrawings. The components in the drawings are not necessarily to scale,emphasis instead being placed upon clearly illustrating the principlesof the present invention. In the drawings, like reference numeralsdesignate corresponding parts throughout the several views.

FIG. 1 is a perspective rear view of a mirror glass of an exterior rearview mirror for a motor vehicle showing essential parts of an apparatusfor mounting the mirror glass to a body of a motor vehicle not depictedhere.

FIG. 2 is a rear view of a mirror glass of an exterior rear view mirrorfor a motor vehicle having a same viewing direction as FIG. 1 andshowing an embodiment of the apparatus for mounting the mirror glass tothe body of the motor vehicle, which comprises a vibration absorber.

FIG. 3 shows the mirror glass and the apparatus according to FIG. 2 in aside view.

FIG. 4 is a perspective rear view of a mirror glass of an exterior rearview mirror for a motor vehicle with an embodiment of the apparatus formounting the mirror glass to a body of the motor vehicle, in whichactivatable functional materials are integrated in an elasticarrangement of the apparatus.

FIG. 5 is a perspective rear view of a mirror glass of an exterior rearview mirror for a motor vehicle showing essential parts of an embodimentof the apparatus for mounting the mirror glass to the body of the motorvehicle. This embodiment—instead of spiral-shaped leaf-springs which areprovided in the embodiments of FIG. 1 to 4—includes pairs of bendingbeams stiffened by stringers. Additionally, FIG. 5 indicates anpositioning device for the mirror glass.

FIG. 6 shows the mirror glass with the bending beams according to FIG. 5but without the stringers.

FIG. 7 is a perspective rear view of a mirror glass of an exterior rearview mirror for a motor vehicle showing essential parts of an embodimentof the apparatus for mounting the mirror glass to the body of the motorvehicle. This embodiment includes a pair of quadruple helices ofopposite pitch connected in series.

FIG. 8 is a perspective rear view of a mirror glass of an exterior rearview mirror for a motor vehicle showing essential parts of an embodimentof the apparatus for mounting the mirror glass to the body of the motorvehicle. This embodiment includes three parallel connected pairs ofquadruple helices of opposite pitch connected in series.

FIG. 9 is a longitudinal section through a rear view mirror for a motorvehicle including an embodiment of the apparatus for mounting its mirrorglass to the body of the motor vehicle. This embodiment being based onparallel connected pairs of triple helices of opposite pitch connectedin series.

FIG. 10 is a perspective view of an exterior rear view mirror for amotor vehicle with viewing direction onto the mirror glass. Theapparatus for mounting the mirror glass to the body here compriseselastomeric springs distributed over the circumference of the mirrorglass.

FIG. 11 is a longitudinal section through the exterior rear view mirroraccording to FIG. 10.

FIG. 12 is a perspective view of another embodiment of the apparatus formounting an object to a structure; and

FIG. 13 is a perspective view of even another embodiment of theapparatus for mounting an object to a structure. This embodiment, naddition to the embodiment of FIG. 12, is provided with a vibrationabsorber.

DETAILED DESCRIPTION

With regard to mounting an object to a structure, the term “in avibration-free manner” here both relates to avoiding the transfer ofvibrations from the structure to the object or vice versa and tocounter-acting any undesired vibrations of the object.

With regard to avoiding the transfer of vibrations from the structure tothe object, the present invention for example relates to mounting amirror glass of an exterior rear view mirror of a motor vehicle to thebody of the motor vehicle. This particular application of the presentinvention, however, should only be taken as an example. It is notintended as a limitation to the present invention.

A mount for the mirror glass of an exterior rear view mirror of a motorvehicle is a typical example of a system in which both a root pointexcitation coming from the supporting structure and an excitation byexternal forces, here particularly by aerodynamic loads, may take place.If these excitations result in vibrations of the mirror glass of theexterior rear view mirror, the mirror image visible in the mirror glassis shaking of blurred. This causes considerably safety risks in roadtraffic.

Other possible applications of the present invention with regard toavoiding the transfer of vibrations from the structure to the objectinclude mounting sensors or handles to hammering or shaking applianceslike, for example, jackhammers.

Other possible applications of the present invention with regard toavoiding the transfer of vibrations from the object to the structureinclude mounting hammering or shaking appliances as well as any motorsto fixed or mobile structures and mounting the stators of rotarybearings of rotors of wind power plants to their pylons.

The apparatus for mounting an object to a structure in a vibration-freemanner according to the present invention comprises an elasticarrangement which supports the object at the structure in a stiff mannerin the directions of at least two of the total of six translational androtational degrees of freedom, and in a stiff manner in the directionsof at least one, often at least two of the total of six translationaland rotational degrees of freedom. The main modes of motion of theobject in the directions of the hard or stiff support comprise aneigenfrequency which is higher than the eigenfrequencies of the mainmodes of motion of the object in the directions of the soft support atleast by a factor of ten; and the soft support as such is not damped,i.e. it is undamped. Instead, an attenuation device is provided forvibrations of the object in those directions in which the object issupported at the structure in a soft manner, i.e. in a soft elastic way.

The elastic arrangement of the apparatus of the present inventionclearly distinguishes between degrees of freedom in which the object issoftly supported at the structure, and degrees of freedom in which theobject is supported at the structure in a hard or stiff manner. Lookingat the total of six translational and rotational degrees of freedomconsisting of three translational degrees of freedom, i.e. linearmovements in the three directions of space, and three rotational degreesof freedom, i.e. rotational movements about the three directions ofspace, the soft support and the stiff support may both be given in thedirections of at least two degrees of freedom.

Typically, the directions of the soft support include those of onetranslational degree of freedom and two rotational degrees of freedomabout the two axes which are orthogonal to the direction of thetranslational degree of freedom; whereas the stiff support is present inthe direction of the remaining two translational and one rotationaldegrees of freedom.

The soft support has the function of elastically decoupling the objectfrom the structure in the directions of the respective degree offreedom. Correspondingly, this soft support is selectively to beprovided in those directions in which the object may be excited forvibrations by the vibrating structure or vice versa. The decouplingprovided by the soft support results in a vibration isolation of theobject from the structure in these directions. It is clear that thisonly applies to frequencies above the eigenfrequency of the main modesof motion of the object in the directions of the soft support. Theseeigenfrequencies of the object in the directions of the soft supportmay, however, be set so low by purpose that they are below thefrequencies at which the structure vibrates.

Additionally, the attenuation device is provided for the main modes ofmotion of the object in the directions of the soft support, andcompensates for any excitations in the area of low frequencies which aretransferred from the structure to the object.

Whereas the directions of the soft support are those directions in whichthe vibrations of the structure are to be isolated from the object, thedirections of the hard or stiff support are those in which the objectshould follow the structure in case of any movement of the structureand/or in which the object should be rigidly supported at the structurewith regard to external forces.

It is particularly preferred in the apparatus according to the presentinvention that the main modes of motion of the object in the directionsof the soft support are decoupled from each other. This means that adisplacement of the object in the direction of one degree of freedomdoes not automatically result in a displacement in the direction of anyother degree of freedom. An even farther reaching separation is achievedby eigenfrequencies of the different main modes of motion separated fromeach other by a clear distance in the frequency space. This decouplinginhibits that a mutual excitation of the main modes of motion of theobject takes place. This makes it easier to dampen the main modes ofmotion of the object in the directions of the soft support by means ofthe attenuation device. Particularly, with separated eigenfrequencies ofthe different main modes of motion, it is sufficient that the absorberdevice—with regard to the frequency space—attenuates movements of theobject in a narrow band around these eigenfrequencies.

Such a narrow band attenuation may, for example, be achieved by a dampedpassive vibration absorber which has an absorber eigenfrequency adjustedto the eigenfrequencies of the main modes of motion of the object in thedirections of the soft support. Such a vibration absorber may have oneor a plurality of absorber masses elastically coupled to the object. Dueto the damping of the vibration absorber, it does not only comprise anabsorber efficiency exactly at its absorber eigenfrequency but also in afrequency band extending around its absorber eigenfrequency. Ideally,the absorber eigenfrequencies of the vibration absorber are adjusted toa value which is a little bit lower, like for example by 5% to 25%, thanthe eigenfrequency of the main modes of motion of the object in thedirections of the soft support. In this way the frequency band withabsorber efficiency is optimally adjusted to the main modes of motion.

The attenuation factor of the damped vibration absorber determinedaccording to Lehr is preferably smaller than about 0.5. Often it issmaller than 0.4 or even lower.

The vibration absorber of the apparatus according to the presentinvention may comprise a single absorber mass for attenuating the objectin all directions of its soft support, if the absorber mass is coupledto the object via a further elastic arrangement which is equivalent tothe elastic arrangement via which the object is mounted to thestructure. This equivalence particularly relates to the degrees offreedom in which the absorber mass is supported at the object in a stiffway and in a soft way, respectively. It does not relate to the dampingof the support.

The absorber mass or absorber masses of the vibration absorber may alsobe used for at least partially counter-balancing the object with regardto its connection to the elastic arrangement. This includes a dynamiccounter-balance with regard to common movements of the object and thestructures in the directions of the hard support.

With regard to the particular application example of an exterior rearview mirror whose mirror glass is to be supported at the body of a motorvehicle or with regard to other cases in which a vibration of the objectin a typical range of some 10 Hz is to be suppressed, the main modes ofmotion of the object in the directions of the soft support may, forexample, have eigenfrequencies of not more or even less than about 10Hz, and the main modes of motion of the object in the directions of thehard support may, for example, have eigenfrequencies of not less or evenmore than about 100 Hz.

The function of the apparatus according to the present invention alsorelies on a certain weight of the mounted object, particularly if theattenuation device comprises an vibration absorber with one or moreabsorber masses elastically coupled to the object. A typical minimumweight of the object is at least about 100 g. Preferably it is about 200g or even higher. In principle, there is no upper limit for the weightof the object. The apparatus according to the present invention may alsobe used for mounting very heavyweight objects to a structure, up to aweight of some tons.

In the following, particular embodiments of the elastic arrangementbetween the object and the structure will be explained.

One of these embodiments comprises two spring elements which are fixedto one or both of the structure and the object in fixing areas which areopposing each other across a center of weight of the object. These twospring elements may, for example, be double springs with two or morebending beams supported at each other via stringers.

It is particularly preferred that the spring elements are leaf springswhich are spirally wound within each other in a common leaf plane. Suchleaf spring arrangements are very stiff with regard to the translationaldegrees of freedom with directions in the leaf plane and the rotationaldegree of freedom about the direction orthogonal to the leaf plane. Withregard to the three other degrees of freedom, the support provided bythe leaf springs, however, is very soft. By using at least two leafsprings wound within each other, a decoupling of the directions of thesoft support of the object is achieved in that a displacement of theobject in the one direction of the soft support does not automaticallyresult in a displacement of the object in any other direction of thesoft support.

Such a decoupling is also achieved with an elastic arrangement which hastwo multiple helices of opposite pitches which are connected in seriesbetween the structure and the object. Such multiple helices aregenerally known as construction elements, see DE 100 26 169 C2, DE 10026 178 C2 and DE 100 26 119 A1, but not in a series connection withopposite pitches.

A further embodiment of the elastic arrangement of the apparatus of thepresent invention comprises elastomeric springs which are connected to arigid inner circumference and to a rigid outer circumference of theobject and the structure, respectively, and which are distributed overthe two circumferences. These elastomeric springs should be soft withregard to tensile load, i.e. have a low tensile stiffness, and they maybe subjected to a pressure prestress between the two circumferences.

The elastic arrangement of the apparatus according to the presentinvention may not only comprise one but even more parallel connecteddiscrete partial elastic arrangements to, for example, limit thebuilding size of each partial arrangement in case of a big and heavyobject to be mounted.

Besides passive elements, the elastic arrangement may also includeactivatable functional materials. These activatable functional materialsmay be part of the attenuation device. For example, they may be part ofa passive absorber device in which the functional materials arecomponents of a mechanical-electrical resonant circuit, or of an activeattenuation device in which the functional materials are activated foran active attenuation of movements of the object in the directions ofthe soft support. In the latter case, the functional materials are forexample used to generate forces onto the object which keep it in rest,or they compensate for relative movements between the object and thestructure in the sense of an infinitely soft spring to avoid thetransfer of forces between the object and the structure. Preferably, thefunctional materials are arranged in such a way that they generatemovements and/or forces between the object and the structure in thedirections of the soft support when they are activated. The functionalmaterials may also be integrated into a further elastic arrangementwhich couples an absorber mass of a passive vibration absorber to theobject to actively move the absorber mass of the vibration absorber.However, in case of an active attenuation device, an additional absorbermass is not needed. Thus, the functional materials are preferablyintegrated into the elastic arrangement in such a way that a passivevibration absorbers for the object is not necessary to dampen the mainmodes of motion of the object in the directions of its soft support. Forthis purpose, the functional materials may, for example, be laminated tospiral-shaped leaf springs of the elastic arrangement.

As already indicated, one possible application of the apparatusaccording to the present invention is mounting the mirror glass, i.e.the reflecting plate, of an exterior rear view mirror to the body of amotor vehicle. Here, the directions of the soft support are particularlythose of one translational degree of freedom parallel to the vehiclelongitudinal axis and of two rotational degrees of freedom about thevehicle cross axis and the vehicle vertical axis. An exact match of thedirections of the soft support with said axes, however, is notimportant.

In an exterior rear view mirror including the apparatus according to thepresent invention supports the mirror glass at a mirror holder, i.e. atan interface of the exterior rear view mirror facing the mirror glass.

The mirror holder is typically at least partially enclosed by a mirrorhousing, and swivel-mounted to the mirror housing via an positioningdevice. This positioning device is thus located at that side of theapparatus according to the present invention facing away from the mirrorglass and extending towards the body of the motor vehicle. Here, afolding hinge may also be provided about which the entire mirror housingcan be folded-in with regard to the body of the motor vehicle.

Preferably, the mirror glass of the exterior rear view mirror isinwardly offset with regard to at least one of a rim of the mirrorholder and a rim of the mirror housing. The mirror glass is thusprotected by the mirror housing or the mirror holder not only withregard to direct aerodynamic loads but also with regard to vorticeswhich are formed at the rim of the mirror housing or the mirror holderas they do not hit the inwardly offset mirror glass. Only pressurefluctuations resulting from these vortices may result in root pointexcitations of the mirror glass. With regard to such root pointexcitations, however, the mirror glass is supported via the apparatusaccording to the present invention in an ideal manner, i.e. in anideally decoupled and attenuated way.

In another application, the apparatus according to the present inventionis part of a wind power plant and is here used for mounting a rotationbearing of a rotor rotating about a rotor axis at a pylon of the windpower plant in a vibration-free manner. In this application, it is aparticular goal to avoid that the aerodynamic excitations of the rotorcause any damages. Such damages may not only occur in the area of therotation bearing or the entire nacelle at the free end of the pylon butalso in the area of the foundation of the pylon or the pylon itself. Therotation bearing for the rotor rotating about the rotor axis oftenincludes a gear box increasing the rotational speed of the rotor andsometimes even a generator driven by the rotor if their stators arefixed to the stator or even make up the stator of the rotational bearingof the rotor. In case of a wind power plant, the directions of the softsupport by the elastic arrangement of the apparatus according to thepresent invention are preferably those of a translational degree offreedom in the direction of the rotor axis and of two rotational degreesof freedom about the vertical axis and the horizontal axis runningorthogonal thereto.

A further application of the apparatus according to the presentinvention is a motor bearing for mounting a motor comprising a rotorrotating about a rotation axis to a fixed or moving structure in avibration-free manner. The motor may, for example, be the motor of amotor vehicle or a stationary motor. In any case, it has to be avoidedthat the motor excites the structure for vibrations. For this purpose,the directions of the soft support by the apparatus according to thepresent invention are preferably those of a translational degree offreedom in the direction of the motor axis and of two rotational degreesof freedom about two axes running orthogonal to the motor axis and toeach other.

The apparatus according to the present invention may further be appliedfor mounting a hammering or shaking device comprising a mass which isrepeatedly accelerated in the direction of a main axis to a fixed ormoving structure. Such appliances are also designated as shakers orhammer mechanisms. They include forging hammers and similar hammeringtools. In these cases the directions of the soft support by the elasticarrangement of the apparatus according to the present invention arepreferably those of a translational degree of freedom in the directionof the main axis and of two rotational degrees of freedom about the axesorthogonal to the main axis and orthogonal to each other.

The apparatus according to the present invention may also be used formounting an object to a hammering or shaking device comprising a massrepeatedly accelerated in the direction of a main axis to, for example,mount a shock-sensitive instrument to such an appliance, like forexample a sensor or also a handle bar which should not be subjected tothe shocks of the mass for protecting a hand gripping the handle. Alsoin theses cases the directions of the soft support are preferably thoseof the translational degree of freedom in the direction of the main axisand of two rotational degrees of freedom about the axes orthogonal tothe main axis and orthogonal to each other.

In another embodiment of the apparatus for mounting an object to astructure comprising at least two elastic partial arrangements arrangedat a distance in the direction of a main axis, the elastic partialarrangements are soft in the direction of the main axis and stifforthogonal to the main axis. The elastic partial arrangements each havean inner connection area close to the main axis and an outer connectionarea at a distance to the main axis. Further, each elastic partialarrangements has at least two spiral-shaped leaf springs which extend ina common leaf plane between the connection areas, and which are spirallywound into each other. These at least two, preferably also exactly twoleaf springs of each elastic partial arrangement of this embodiment ofthe apparatus according to the present invention result in a very softsupport of the object at the structure along the main axis, whereas theobject is stiffly guided at the structure in all other directions. Dueto their spiral shape, the leaf springs are comparatively long and maythus provide the soft support in the direction of the main axis overquite a long way.

Preferably, the width of the leaf springs of the apparatus according tothe present invention does not increase with increasing distance to theaxis like in case of a spiral-cut diaphragm. Instead, the width of theleaf springs is constant or even decreases with decreasing distance tothe axis.

Preferably, the leaf springs—in circumferential direction about theaxis, and with regard to the angular distance between their innerconnection area close to the axis and their outer connection areafarther away from the axis—span an angle in a typical range of 180° to270°. This angle should not be much smaller to ensure the soft supportin the direction of the main axis. It should, however, also not be muchbigger as this would reduce the stiffness of the guiding in thosedirections orthogonal to the axis.

The leaf springs of each element may in every aspect be rotationalsymmetric with regard to the main axis, i.e. particularly both withregard to their construction and their distribution around the mainaxis.

Even in case of more than two leave springs per each elastic partialarrangement, these leaf springs are preferably arranged at a maximumdistance in circumferential direction about the axis. This also meansthat they are preferably uniformly distributed around the axis. Thus,the formation of any predominant direction orthogonal to the main axisis avoided. In this context it should be mentioned that the apparatusaccording to the present invention generally displays no tendency to theformation of predominant directions, and thus—as a rule—only needs twoleaf springs per each elastic partial arrangement and does not requireat least three leaf springs, for example.

The leaf springs may be part of a single one-piece leaf spring unit perelastic partial arrangement. Such a leaf spring unit or even theindividual leaf springs may be made of a metallic material or of a fibercompound material, for example.

The distance between the at least two elastic partial arrangements inthe direction of the main axis is preferably at least twice as big asthe distance between the outer connection area to the inner connectionarea in radial direction to the axis. The longer the distance betweenthe two elastic partial arrangements in the direction of the main axis,the stiffer is the guiding of the object at the structure with regard totilting movements of the object about tilting axes orthogonal to themain axes.

In one application of this embodiment of the apparatus according to thepresent invention, the inner connection area of each spring element hasa common connection interface or connector for all leaf springs, whereasthe outer connection area of each spring element has one separateconnection point for each leaf spring. Due to the greater distance ofthe leaf springs at the outer connection area in circumferentialdirection about the main axis, a connection area continuously runningaround the main axis would be unnecessarily complex. Additionally,further parts of the apparatus according to the present invention may beprovided between separate connection points for each leaf spring in theouter connection area.

This is particularly advantageous when an absorber mass of a vibrationabsorber is elastically coupled to the object via at least two furtherelastic partial arrangements arranged at a distance in the direction ofthe axis. This vibration absorber absorbs vibrations of the object inthe direction of the main axis which are still transferred to the objectfrom the structure or otherwise.

Preferably, the further elastic partial arrangements are equal orequivalent to the elastic partial arrangements. Thus, the eigenfrequencyof the vibration absorber may be simply adjusted to the eigenfrequencyof the object by means of the weight of the absorber mass so that amaximum efficiency of the vibration absorber is achieved.

A particularly compact construction results, if the leaf springs of oneelastic partial arrangement for supporting the object at the structureand of one further elastic partial arrangement coupling the absorbermass to the object are spirally wound into each other, and have a commonconnection interface or connector to the object. This common connectorparticularly is the common inner connection area of the respectiveelastic partial arrangements. In the common outer connection areafarther away from the main axis, a connection point of the one elasticpartial arrangement to the structure follows to one connection point ofthe one further elastic partial arrangement to the absorber mass.

The leaf springs of the one elastic partial arrangement and thecorresponding one further elastic partial arrangement spirally woundinto each other may be parts of a single one-piece leaf spring unitresulting in a particularly simple construction of the apparatusaccording to the present invention comprising the vibration absorber.

Additionally, a damping may be effective between the connection areas ofthe elastic partial arrangements. This does not only apply to theelastic partial arrangements which support the object at the structurebut also for the further elastic partial arrangements which couple theabsorber mass of the vibration absorber to the object. Such a dampingdissipates kinetic energy, particularly vibration and shock energy, andthus avoids high amplitudes of the relative movement of the object withregard to the structure or of the absorber mass with regard to theobject.

Particularly, the damping may be provided magnetically or by means ofinner damping of the leaf springs or by means of a damping materialapplied to at least one of the leaf springs of at least one elasticpartial arrangement or further elastic partial arrangement. For example,a certain damping may be achieved in that metallic leaf springs areprovided with a coating of an elastomer material. Generally, even anadditional hydraulic or pneumatic shock absorber may be active betweenthe object in the structure in the direction of the main axis.

Further, in the apparatus according to the present invention, at leastone leaf spring may be actively deformable to for example activelyattenuate movements of the object with regard to the structure. For thispurpose, an active functional material may be applied to the leafspring. For example, the leaf spring may be coated with a piezo-electricmaterial including control electrodes which deforms the leaf spring uponactivation by applying a voltage to the control electrodes according theso-called bi-metal principle.

Now referring in greater detail to the drawings, FIG. 1 is a perspectiveview onto the back side of a mirror glass 1 of an exterior rear viewmirror of a motor vehicle. An apparatus 2 is provided for mounting themirror glass 1 via a mirror holder to the body of the motor vehicle notdepicted here. The apparatus 2 comprises two interfaces 3 to be fixed tothe mirror holder or to points which are fixed with regard to the bodyof the motor vehicle. One spiral-shaped leaf spring 4 extends away fromeach of the two interfaces 3. Both leaf springs 4 have a same spiralaxis 5 across which the two interfaces 3 are diametrically facing eachother. The spiral axis 5 is orthogonal to a mirror plane 6 of the mirrorglass 1, and it runs through the center of weight of the mirror glass 1.In an unloaded state of the leaf springs 4, their directions of mainextension run in a common leaf plane which is orthogonal to the spiralaxis 5 and thus parallel to the mirror plane 6. In the area of thespiral axis 5, i.e. close to the spiral axis 5, the mirror glass 1 isconnected to both leaf springs 4 via a common interface 7 or connectorin a fixed way. On that side of the leaf plane of the spiral springs 4that is opposite to the mirror plane 1, the interface 7 provides a mass8 for counter-balancing the weight of the mirror glass 1. The apparatus2 guides the mirror glass 1 stiffly with regard to the translationaldegrees of freedom in all directions parallel to the mirror plane 6 andwith regard to the rotational degree of freedom about the spiral axis 5.In the directions of the remaining three degrees of freedom, i.e. of thetranslational degree of freedom in the direction of the spiral axis 5and the two rotational degrees of freedom about two axes orthogonal tothe spiral axis 5 and orthogonal to each other, however, the apparatus 2soft elastically supports the mirror glass 1. The main modes of motionin the directions of all these degrees of freedom are decoupled; i.e. adisplacement in the direction of one degree of freedom does notautomatically result in a displacement of the mirror glass 1 in thedirection of another degree of freedom. The stiff support in selecteddirections cares for that the mirror glass 1 directly follows anymovements of the body of the motor vehicle in these directions and thatthe mirror glass 1 is stiffly supported with regard to any externalloads and forces. The soft support in the other directions results in avibration isolation of the mirror glass 1 from the body of the motorvehicle at all frequencies above the low eigenfrequencies of this softsupport.

To also avoid undesired vibrations of the mirror glass 1 at these loweigenfrequencies, the apparatus 2 comprises an attenuation device forthe main modes of motion of the mirror glass 1 in the directions of thesoft support which is not depicted in FIG. 1. This attenuation devicemay include a vibration absorber 9 as depicted in FIGS. 2 and 3,which—at that side of the leaf plane of the spiral springs 4 opposingthe mirror glass 1—is connected to the interface 7 and thus also acts asan additional counter-balancing mass 8 for the weight of the mirrorglass 1. An absorber mass 10 of the vibration absorber 9 is coupled tothe interface 7 via a further elastic arrangement which is equivalent tothe elastic arrangement of the leaf springs 4 in that it also consistsof spiral-shaped leaf springs 11 with a common center on the spiral axis5. A leaf plane of the spiral springs 11 is parallel to the leaf planeof the spiral springs 4; and the spiral springs 11 are to the interface7 at their common center in the area of the spiral axis 5 and to theabsorber mass 10 at connection points 12 facing each other across thespiral axis 5. The vibration absorber 9 comprises three absorber mainmodes with absorber eigenfrequencies which are adjusted to the threemain modes of motion and the associated eigenfrequencies of the mirrorglass 1 in the directions of the soft support by the apparatus 2. Thevibration absorber 9 thus keeps the mirror glass 1 at rest with regardto these main modes of motion of the soft support.

The embodiment of the apparatus 2 for mounting the mirror glass 1 in avibration-free manner according to FIG. 4 also bases on that oneaccording to FIG. 1. Here, the counter-balancing mass 8 includes afurther body 13 rigidly connected to the interface 7. The attenuationdevice consists of functional material in form of so-called piezopatches 21 to 26 integrated in the elastic arrangement of the leafsprings 4. The piezo patches 21 to 26 are laminated to the spiral-shapedleaf springs 4 and comprise a piezo-electric layer between two controlelectrodes. This layer expands in parallel to the surface of the leafsprings 4 upon application of an external voltage to the controlelectrodes. As a result, the leaf springs 4 are deformed according tothe principles of a bi-metal. Thus, movements of the mirror glass 1 maybe initiated and existing vibrations of the mirror glass 1 may beactively extinguished. The individual piezo patches 21 to 26 may beselectively controlled for extinguishing vibrations in the directions ofthe soft support by the apparatus 2. Particularly, for a movement aboutthe vertical axis orthogonal to the spiral axis 5, only the piezopatches 22 and 25 are to be activated in opposite directions. For amovement about the cross axis orthogonal to the spiral axis 5, only thepiezo patches 23 and 26 are to be activated in opposite directions; andfor a movement in the direction of the spiral axis 5, the piezo patches21 and 24 are to be operated in opposite directions. As for each ofthese movements another pair of piezo patches 21 to 26 is to beselectively activated, vibrations in the directions of these movementsmay be actively attenuated independently from each other by operatingthe respective piezo patches in antiphase with the existing movements ofthe mirror glass 1.

FIG. 5 shows another embodiment of the apparatus 2 for mounting themirror glass 1 to the body of a motor vehicle which comprises the samedirections of hard or stiff and soft support as the embodiments of theapparatus 2 according to FIG. 1 to 4. The interfaces 3 are here providedin two opposing boundary areas of the mirror glass 1 and are supportedat a mirror holder 14. The mirror holder 14 is configured to be mountedto the body of the motor vehicle via a positioning device 15 forpositioning the mirror glass 1 with regard to the body of the motorvehicle. Such a positioning device is generally known and typicallyincludes one or more electric servo motors. Double springs 16 extendfrom the interfaces 3 towards the interfaces 7 which are arranged inopposing boundary areas of the mirror glass 1. The construction of eachdouble spring 16 is based on two bending beams 17 which are parallel toeach other and which are stiffened in that they are supported at eachother by stringers 18.

In FIG. 6 the bending beams 17 are depicted without the stringers 18.The bending beams 17 and the stringers 18 may completely consist ofsteel or plastic. Alternatively, the bending beams 17 may consist ofsprings steel to which the stringers 18 are injection-molded of plastic.The stringers 18 stiffen the spring elements 16 in those directions ofthe desired stiff support of the mirror glass 1 at the mirror holder 14shown in FIG. 5. The spring elements 16, however, remain soft for thosedirections of the desired soft support.

The embodiment of the apparatus 2 for mounting the mirror glass 1 to thebody of a motor vehicle in a vibration-free manner according to FIG. 7is based on a pair of quadruple helices of opposing pitches connected inseries. Here, these quadruple helices are each condensed to four leafspring sections 19 which are arranged in a rotation-symmetricarrangement around a helix axis 20 and which are each swivel-mounted toone of the interfaces 3 and 7 and to an intermediate element 21 aboutaxes orthogonal to the helix axis 20. The pitch of the leaf springsections 19 extending from the interface 3 to the intermediate element21 is opposite to the pitch of the leaf spring sections 19 extendingbetween the intermediate element 21 and the interface 7. As a result, alinear movement of the mirror glass 1 in the direction of the helix axis20 results in a rotation of the intermediate element 27 about the helixaxis 20 but does not initiate a rotational movement of the mirror glass1 about the helix axis 20. Thus, the directions of the soft and the hardsupport of the mirror glass 1 at the body of the motor vehicle are thesame as in case of the previous embodiments of the apparatus 2; and theapparatus 2 according to FIG. 7 decouples the main modes of motion ofthe mirror glass 1 relative to the body of the motor vehicle.

FIG. 8 illustrates a variant of the apparatus 2 according to FIG. 7 inwhich in total three pairs of two quadruple helices with leaf springsections 19 of opposite pitch connected in series are provided anddistributed over the back side of the mirror glass 1. The helix axes 20of the pairs of multiple helices of opposing pitch are parallel to eachother and orthogonal to the mirror plane 6 of the mirror glass 1. Due tothe plurality of the pairs of multiple helices of opposing pitch, thestiffness of the support of the mirror glass 1 with regard to movementsparallel to the mirror plane 6 is increased. Such a parallel connectionof a plurality of elastic partial arrangements which could alsoindividually be used as elastic arrangements of the apparatus 2 is aparticular advantage, if an object to be mounted has big dimensionsand/or a high weight. Preferably, the elastic partial arrangements aresymmetrically arranged with regard to a main axis which coincides with atranslational degree of freedom in whose direction the apparatus 2provides soft support.

The exterior rear view mirror 32 of a motor vehicle depicted in FIG. 9in a longitudinal section comprises a mirror housing 28 to which themirror holder 14 is mounted via the positioning device 15, i.e.adjustable about two axes. The mirror housing 28 partially encloses themirror holder 14 which itself is designed as an open housing. The mirrorglass 1 is inwardly offset into the mirror holder 14 with regard to arim 33 of the mirror holder 14. However, it is still positioned in frontof a rim 34 of the mirror housing 28 here. Nevertheless, the mirrorglass 1 is protected by the mirror housing 28 against direct aerodynamicloads, i.e. against an excitation by wind which, in FIG. 9, goes fromleft to right. The mirror holder 14 with its protruding rim 33additionally protects the mirror glass 1 against vortices generated atthis rim 33. Aerodynamic pressure fluctuations may nevertheless cause anexcitation of the mirror holder 14 for vibrations. These vibrations,however, are not transferred to the mirror glass 1 as the mirror glass 1is mounted via the apparatus 2 to the mirror holder 14 in an optimallydecoupled and attenuated way with regard to such root point excitations.According to FIG. 9, the apparatus 2 is based on pairs of triple helicesof leaf springs 19 of opposing pitch with intermediate elements 27.

FIGS. 10 and 11 show an entire exterior rear view mirror 32 in which thedirection-selective hard and stiff support of the mirror glass 1 at themirror holder 14 is provided by means of elastomeric springs 29. Theelastomeric springs 29 are arranged between a rigid outer circumference30 of the mirror glass 1 and a rigid inner circumference 31 of themirror holder 14 and essentially extend within or close to the mirrorplane 6. Due to a low tensile stiffness of the elastomeric springs 29which may be supplemented by some pressure prestress onto theelastomeric springs 29 between the circumferences 30 and 31, the samedirections of hard of stiff and soft support are realizes as in case ofthe previously describes embodiments of the apparatus 2 for mounting themirror glass 1 of an exterior rear view mirror to the body of a motorvehicle in a vibration-free manner. The mirror housing 28 is connectedto the respective body of the motor vehicle via a base 35. The base 35may include a folding hinge for folding in the exterior rear view mirror32 towards the body. In FIG. 11 a wind excitation 36 of the exteriorrear view mirror 32 and vortices 37 which are generated at the rims 33and 34 of the mirror holder 14 and the mirror housing 28 are indicated.The mirror glass 1 is here offset into the exterior rear view mirror 32to such an extent that it is also set back with regard to the rim 34 ofthe mirror housing 28 and thus protected against any direct influence ofthe vortices 37.

In the embodiments of FIG. 5 to 11 the attenuation device of theapparatus 2 which keeps the mirror glass 1 at rest even at theeigenfrequencies of its soft support is not depicted but maynevertheless be provided.

The apparatus 101 depicted in FIG. 12 serves for mounting an object 102to a structure 103. The support of the object 102 at the structure 103is soft in the direction of a main axis 104 and stiff in all otherdirections. Thus, the object 102 is linearly guided at the structure 103in the direction of the axis 104. This means that both linear ortranslational movements of the object 102 relative to the structure 103in all directions orthogonal to the main axis 104 and rotations of theobject 102 relative to the structure 103 about the axis 104 and anytilting axes orthogonal to the main axis 104 are prevented at a highstiffness. Linear movements of the object 102 in the direction of themain axis 104, however, are possible with low forces which only increasewith high displacements of the object 102 relative to the structure 103in the direction of the main axis 104. This distribution of thestiffnesses ensures a decoupling of the object 102 with regard tovibrations and shocks of the structure 103 in the direction of the mainaxis 104. The appropriate stiffnesses are provided by two elasticpartial arrangements 105. Each elastic partial arrangements 105comprises a leaf spring unit 106 of a plane basic form in which it isdepicted in FIG. 12. Each leaf spring unit 106 comprises two leafsprings 107 which are spirally wound into each other about the main axis104 and which extend from a common inner connection area 108 to separateconnection points 109 in an outer connection area. The inner connectionarea 108 is rigidly connected to the object 102, whereas the connectionspoints 109 are rigidly connected to the structure 103. Each leaf spring107 spans an angle of more than 180° in the circumferential directionabout the main axis 104, and it comprises an essentially constant widthin the leaf plane of the respective leaf spring unit 106. Thearrangement of the two leaf springs 107 of each leaf spring unit 106 is180° rotation symmetric with regard to the main axis 104. All leafsprings 107 of both elastic partial arrangements 105 have a same pitchor spiral direction about the main axis 104. The distance of the twoelastic partial arrangement 105 along the axis 104 is more than twice ashigh than the distance of the connection points 109 to the connectionarea 108 in radial direction to the main axis 104.

FIG. 13 shows an embodiment of the apparatus 101 which, compared to FIG.12, is supplemented with a vibration absorber 110. The vibrationabsorber 110 comprises an absorber mass 111 which is tube-shaped andcoaxially arranged around the object 102. The absorber mass 111 iselastically coupled to the object 102 by means of two further elasticpartial arrangements 112. This support is also soft in the direction ofthe main axis 104 but stiff otherwise. This is achieved in that thefurther elastic partial arrangements 112 each comprise leaf springs 113which are equal to the leaf springs 107 of the elastic partialarrangements 105. Particularly, the leaf springs 113 are also parts ofthe leaf spring units 106 and spirally extend from the common connectionarea 108 close to the main axis 104 towards outer connection points 114,where they are rigidly connected to the absorber mass 111. In each leafspring unit 106, one leaf spring 113 follows to each leaf spring 107 andvice versa in circumferential direction around the main axis 104. Allpairs of leaf springs 107 and 113 succeeding in circumferentialdirection around the main axis 104 display same angular distancesbetween the leaf springs 107 and 113. The vibration absorber 110 absorbsvibrations of the object 102 in the direction of the main axis 104, i.e.these vibrations are absorbed by the absorber mass 111 so that theabsorber mass 111 exerts antiphased forces onto the object 102, and thuskeeps the object 102 at rest. Additionally, a damping for the movementof the absorber mass 111 and/or the object 102 in the direction of themain axis 104 may be provided (not depicted here). Further, activatablefunctional materials may be applied to the leaf springs 107 and/or theleaf springs 113 to actively deform these leaf springs by activating thefunctional materials. In this way, forces between the structure 103 andthe object 102 or the object 102 and the absorber mass 111 maypurposefully be generated to influence their relative movements.

Many variations and modifications may be made to the preferredembodiments of the invention without departing substantially from thespirit and principles of the invention. All such modifications andvariations are intended to be included herein within the scope of thepresent invention, as defined by the following claims.

We claim:
 1. An apparatus for mounting an object to a structure in avibration-free manner, the apparatus comprising: an elastic arrangementcomprising at last two leaf springs which are spirally wound into eachother about a spiral axis within a common leaf plane and which areconnected to both the structure and the object in connection areas whichare facing each other across a center of mass of the object, the at lasttwo leaf springs stiffly support the object at the structure indirections of two translational degrees of freedom parallel to the leafplane and one rotational degree of freedom about the spiral axis andsoft elastically support the object at the structure in directions ofone translational degree of freedom in direction of the spiral axis andtwo rotational degrees of freedom about two axes orthogonal to thespiral axis and orthogonal to each other, wherein the object, in each ofthe directions of the two translational degrees of freedom parallel tothe leaf plane and the one rotational degree of freedom about the spiralaxis, comprises an eigenfrequency which is by a factor of at least tenhigher than any eigenfrequency of the object in each of the directionsof the one translational degree of freedom in direction of the spiralaxis and the two rotational degrees of freedom about two axes orthogonalto the spiral axis and orthogonal to each other, and wherein the elasticarrangement is undamped in each of the directions of the onetranslational degree of freedom in direction of the spiral axis and thetwo rotational degrees of freedom about two axes orthogonal to thespiral axis and orthogonal to each other; and an attenuation device forany motion of the object in the directions of the one translationaldegree of freedom in direction of the spiral axis and the two rotationaldegrees of freedom about two axes orthogonal to the spiral axis andorthogonal to each other.
 2. The apparatus of claim 1, wherein theattenuation device comprises a passive vibration absorber havingabsorber eigenfrequencies adjusted to the eigenfrequencies of the objectin the directions of the one translational degree of freedom indirection of the spiral axis and the two rotational degrees of freedomabout two axes orthogonal to the spiral axis and orthogonal to eachother.
 3. The apparatus of claim 2, wherein the vibration absorber isdamped.
 4. The apparatus of claim 3, wherein an attenuation factor ofthe damped vibration absorber according to Lehr is less than 0.5.
 5. Theapparatus of claim 2, wherein the absorber eigenfrequencies of thevibration absorber are by 5% to 25% smaller than the correspondingeigenfrequencies of the object in the directions of the onetranslational degree of freedom in direction of the spiral axis and thetwo rotational degrees of freedom about two axes orthogonal to thespiral axis and orthogonal to each other.
 6. The apparatus of claim 2,wherein the vibration absorber comprises an absorber mass which iscoupled to the object via a further elastic arrangement, the furtherelastic arrangement being equivalent to the elastic arrangement.
 7. Theapparatus of claim 2, wherein the vibration absorber comprises anabsorber mass which at least partially counter-balances the object withregard to its connection to the elastic arrangement.
 8. The apparatus ofclaim 1, wherein the attenuation device comprises actuators made ofactivatable functional material which is applied to the attenuationdevice.
 9. The apparatus of claim 8, wherein the actuators made ofactivatable functional material are arranged and configured such thattheir activation generates at least one of movements and forces betweenthe object and the structure in at least one of the directions of theone translational degree of freedom in direction of the spiral axis andthe two rotational degrees of freedom about two axes orthogonal to thespiral axis and orthogonal to each other.
 10. The apparatus of claim 9,wherein the attenuation device activates the actuators made ofactivatable functional material in the sense of an active attenuation ofthe object in the at least one of the directions of the onetranslational degree of freedom in direction of the spiral axis and thetwo rotational degrees of freedom about two axes orthogonal to thespiral axis and orthogonal to each other.
 11. The apparatus of claim 1,wherein motions of the objects in the directions of the onetranslational degree of freedom in direction of the spiral axis and ofthe two rotational degrees of freedom about two axes orthogonal to thespiral axis and orthogonal to each other are decoupled from each other.12. The apparatus of claim 1, wherein the object in each of thedirections of the one translational degree of freedom in direction ofthe spiral axis and the two rotational degrees of freedom about two axesorthogonal to the spiral axis and orthogonal to each other has aneigenfrequency of not more than about 10 Hz, and wherein the object ineach of the directions of the two translational degrees of freedomparallel to the leaf plane and the one rotational degree of freedomabout the spiral axis has an eigenfrequency of not less than about 100Hz.
 13. The apparatus of claim 1, wherein the object is a mirror glassof an exterior rear view mirror of a motor vehicle, wherein thestructure is a mirror holder, and wherein the directions of the onetranslational degree of freedom in direction of the spiral axis and thetwo rotational degrees of freedom about two axes orthogonal to thespiral axis and orthogonal to each other are those of a translationaldegree of freedom parallel to a longitudinal axis of the motor vehicleand of two rotations degrees of freedom about a vehicle cross axis and avehicle vertical axis.